The present invention relates generally to a helical scan VTR (video tape recorder), and is directed more particularly to a tape tension control circuit used in a helical scan VTR.
Recently, a helical scan VTR has been employed not only in home use but also in broadcast use. As the helical scan VTR is used in the broadcast field, it becomes necessary that a magnetic tape is transported smoothly in the forward and reverse directions while it is wrapped on a tape guide drum. In the conventional helical scan VTR, the tape tension in the forward running direction is controlled in such a manner that a band brake engaged with a supply reel disc is controlled by a tension sensing arm which touches a magnetic tape extended between a supply reel and the tape guide drum. The tape tension in the reverse direction is controlled such that a tension sensor is provided between the tape guide drum and the take-up reel to control a take-up reel motor. It is, however, impossible to precisely control by the tension sensing arm and the band brake the tape tension in various modes. In addition, the difference between the tape tension control systems at the tape take-up and supply sides results in difficult adjustments and causes problems in manufacturing VTRs and in other situations.